016413   Bhattacharjee A;Verma A L (Phys Dep, St. Anthony's Coll, Shillong-793 001, Email: mrphysics@rediffmail.com) : Degree of charge transfer in the mixed stack donor-acceptor charge transfer complex of C₁₈TCNQ and TMB probed by laser Raman spectroscopy. Indian J Phys 2005, 79(9), 1053-7.

Essentially is a study and confirmation of charge transfer between the 3,3',5,5'-tetrabenzidine and 2-octadecyl 7,7,8,8, tetracyanoquinodimethane (TMB- C₁₈TCNQ) by Raman spectroscopy scattering technique on a cast film of the sample. Organic charge transfer complexes composed of planar aromatic donor (D) and acceptor (A) molecules have been recognised to be of crucial importance due to their unique physical properties which arise from their low dimensionality. A cast film of 2-octadecyl-7,7.6,8 tetracyanoquinodimethane (C₁₈TCNQ) was prepared on a gold coated glass slide and its Raman spectrum was studied using excitation lines from a He-Cd laser (441.6 nm). The cast film of C₁₈TCNQ was then doped with 3,3',5,5' -tetramethylbenzidine (TMB) which resulted in the charge of colour from yellow to purple-red. The shift in the position of the bands in the Raman spectrum of this doped sample revealed the formation of a charge transfer complex. The Raman bands of the pure C₁₈TCNQ sample at 1443 cm^-1 and 2219 cm^-1 were shifted to 1423 cm^-1 and 2203 cm^-1 respectively, after doping with TMB. From a detailed study of these bands, the degree of charge transfer (r) from C₁₈TCNQ to TMB has been estimated.

5 illus, 1 table, 16 ref

016412   Basu M;Das B R (Math Dep, Jadavpur Univ, Kolkata-700 032) : Two-dimensional mixed boundary value heat conduction problem of an infinite strip. Indian J Theor Phys 2005, 53(3), 247-55.

An attempt has been made to solve a steady-state heat conduction problem of an infinite elastic strip. A part of one of its edges is subjected to a prescribed flux of heat and the remaining part of the boundary is kept at zero temperature. The temperature at any point of the strip is expressed in terms of an ingetral and the variation of the temperature on the part of the boundary exposed to the heat flux is shown graphically.

1 illus, 3 ref

016411   Bandopadhyay S (NO, S.N. Bose Natn Cent for Basic Sci, JD Block, Sector III, Salt Lake, Kolkata-700 098) : Phase delay time and superluminal propagation in barrier tunneling. Indian J Phys 2005, 79(9), 953-7.

Behaviour of Wigner phase delay time for tunneling in the reflection mode has been studied. System consists of a circular loop connected to a single wire of semi-infinite length in the presence of Aharonov-Bohm flux. Calculates the analytical expression for the saturated delay time. This saturated delay time is independent of Aharonov-Bohm flux and the width of the opaque barrier thereby generalising the Hartman effect. This effect implies superluminal group velocities as a consequence. Also briefly discusses the concept called space collapse or space destroyer.

5 illus, 19 ref

016410   Aravamudhan S (Chem Dep, North East Hill Univ, NEHU Campus Mawkynroh Umshing, Shillong-793 022, Email: saravamudhana@nehu.ac.in) : Magnetised materials: contributions inside Lorentz ellipsoids. Indian J Phys 2005, 79(9), 985-89.

Lorentz sphere is a hypothetical spherical volume element, inevitably, invoked to take into account the demagnetising effects (in the case of diamagnetic materials) while describing the contributions to the induced fields at a point inside magnetised materials. Till now, there have not been any compelling necessity to know the actual magnetudes of the contributions from within this sphere and, how exactly to demarcate this spherical part of the material by a concrete boundary, within the bulk material of the specimen. Not much emphasis could be given in the discussions on the significance of the Lorentaz sphere, except that, it be defined as a semi-micro volume element. This situation seems to have been brought to prominence by the discussion requiring interpretation of the experimental results by the technique of Solid Stage High Resolution Protein Magnetic Resonance (HR PMR) in single crystals of organic molecules. This perspective has been discussed.

6 illus, 9 ref

015415   Yadav S;Bandyopadhyay A K (Natn Phys Lab, Dr. K.S. Krishnan Rd, New Delhi-110 012, Email: syadav@mail.nplindia.crnet.in) : Interlaboratory comparison in the pressure range 7-70 MPa using digital pressure calibrator. MAPAN 2005, 20(4), 297-310.

Describes the results of a proficiency testing program carried out through interlaboratory comparison of seven laboratories, accredited by National Accreditation Board for Testing and Calibration of Laboratories (NABL), India, having best measurement capabilities better than 0.25 % and coarse than 0.05% of full-scale pressure, using a Digital Pressure Calibrator as an artifact in the pressure range 70 bar to 700 bar (7 MPa to 70 MPa). The primary objective for organizing this proficiency testing (PT) is to assess the laboratory's technical competence to perform measurements and also fulfilling the requirement oflLAC/APLAC in regards to the compatibility of results submitted by these laboratories. National Physical Laboratory (NPLl), New Delhi, India has the responsibility of coordinating this programme and also acted as a reference laboratory. The program was identified by code number NABL-Pressure-PT002. The stability of the artifact was assessed by measurements made at NPLl before and after the circulation of the artifact. The comparison was carried out at 10 arbitrarily chosen pressure points i.e. 7 MPa, 14 MPa, 21 MPa, 28 MPa, 35 MPa, 42 MPa, 49 MPa, 56 MPa, 63 MPa and 70 MPa throughout the entire pressure range. Data are analyzed as per ISO/IEC GUM document. The normalized error (E_n) values are estimated in the entire pressure range. The E_n values of the 30 (53.6%) measurement results out of the total 56 reported herein, arc found in agreement with the reference laboratory. The E_n values of only one laboratory are within acceptable limits through out the entire pressure scale. Overall, the results are considered to be fairly good being the first proficiency testing for all the participating laboratories. This exercise gives an opportunity to calibration laboratory to demonstrate its technical competence of routine calibration services rendered to clients and to have the measurement tracebility to the national metrology institute, NPLI, New Delhi.

9 illus, 7 tables, 21 ref

015414   Sunil;Bharti P K;Sharma R C (Dep of Appl Sci, Natn Inst of Technol (Deemed University), Hamirpur-177 005, Email: sunil @ recham.ernet.in) : On couple-stress fluid heated and soluted from below in porous medium in presence of Hall currents. Indian J Theor Phys 2005, 53(1), 59-78.

A layer of couple-stress fluid heated and soluted from below in porous medium is considered in the presence of uniform vertical magnetic field to include the effect of Hall currents. For the stationary convection case, the magnetic field and stable solute gradient postpone the onset of convection while the Hall current hastens the onset of convection. The medium permeability and couple-stress both postpone and hasten the onset of convection depending on the Hall parameter M. Graphs have been plotted by giving numerical values to the parameters, to depict the stability characteristics. The magnetic field (and corresponding Hall currents) and stable solute gradient are found to indroduce oscillatory modes in the system, which were non-existent in their absense. The sufficient conditions for the non-existence of overstability are also obtained.

6 illus, 19 ref

015413   Sreenivas K;Kumar S;Choudhary J;Gupta V (Dep of Phys and Astrophysic, Univ of Delhi, Delhi-110 007, Email: kondepudysreenivas@rediffmail.com) : Growth of zinc oxide nanostructures. Pramana J Phys 2005, 65(5), 809-814.

Zinc oxide (ZnO) nanowhiskers have been prepared using a multilayer ZnO(50 nm)/Zn(20 nm)/ZnO(2 μm) structure on a polished stainless steel (SS) substrate by high rate magnetron sputtering. The formation of uniformly distributed ZnO nanowhiskers with about 20 nm dia. and 2 to 5 μm length was observed after a post-deposition annealing of the prepared structure at 300-400°C. An array of highly c-axis oriented ZnO columns (70-300 nm in dia. and up to 10 μm long) were grown on Si substrates by pulsed laser deposition (PLD) at a high pressure (1 Torr), and Raman studies showed the activation of surface phonon modes. The nanosized powder (15-20 nm) and nanoparticle ZnO films on glass substrate were also prepared by a chemical route. Nanowhiskers showed enhanced UV light detection characteristics, and the chemically prepared ZnO nanoparticle films exhibited good sensing properties for alcohol.

4 illus, 6 ref

015412   Singh R (NO, , 144, Sundar Nagar, Raipur-492 013) : Noise patterns. Indian J Theor Phys 2005, 53(1), 47-57.

Noise seems to be a penalty of modern life, but recently role played by noise for pattern formation and information processing is attracting the attention of research workers. We have given here the conventional definitions of music and noise in terms of wave forms (oscillations) have been given and have been the underdamped oscillations of the oscillator, with infinite series of Dirac delta functions as impulsive forcing functions by means of Laplace transform for generalized functions. Representation of noise wave forms by random distribution of numerals has also been given.

2 illus, 9 ref

015411   Sharma P R;Gaur Y N;Sharma R P (Dep of Math, Univ of Raj, Jaipur-302 004) : Steady laminar flow and heat transfer of a non-Newtonian fluid through a straight horizontal porous channel in the presence of heat source. Indian J Theor Phys 2005, 53(1), 37-46.

Steady laminar flow and heat transfer of a Second Grade fluid through a straight horizontal porous channel in the presence of heat source when the upper plate is moving in its own plane is investigated. The plates are kept at different constant temperatures. The fluid is injected through the stationary plate at constant rate and sucked through the upper plate at the same rate. The expressions of velocity and temperature fields are derived, discussed numerically and shown through graphs. Also, the expressions of skin-friction and Nueselt number at both the plates are derived, discussed numerically and their numerical values for various values of physical parameters are presented through tables.

2 illus, 2 tables, 19 ref

015410   Sen Gupta A;Hanjura A K (Natn Phys Lab, Dr. K.S. Krishnan Marg, New Delhi-110 012, Email: sengupta@nplindia.ernet.in) : Refining the geostationary satellite orbit determination using multi-station INSAT STFS observations. MAPAN 2005, 20(4), 283-9.

Knowledge of the precise satellite position is a prerequisite for obtaining high time transfer accuracy in the Standard Time and Frequency Signal (STFS) broadcast by the National Physical Laboratory (NPL) via INSAT. A technique of using the multi-station reception of the IN SAT Standard Time and Frequency Signal (STFS) broadcast for the purpose of ranging has been proposed. Using the multi-station ranging data with associated uncertainties that are usually observed for STFS reception data, it is possible to compute the satellite positions periodically. The orbit determination process consists of an iterative algorithm that refines an assumed initial orbit successively to agree with the actual orbit by matching the periodic position data computed and obtained experimentally. Shows by realistic simulations that with only 10 to 15 iterations it is possible to reduce the satellite position uncertainty to within a 200 m cube.

4 illus, 5 ref

015409   Sathtyamoorthi R;Subramania A;Gangadharan R; Vasudevan T (Dep of Industrial Chem, Alagappa Univ, Karaikudi-630 003, Email: drtvasudevan2002@yahoo.com) : Preparation of nanoparticle size LiBiO₂ by combustion method and its electrochemical studies for lithiurn secondary cells. Pramana J Phys 2005, 65(5), 973-80.

A simple combustion method has been tried for the preparation of nanoparticle-sized LiBiO?2 powder with urea as the igniter and glycerol as the binding material. Nitrates of Li⁺ and Bi³⁺ were mixed together to form a uniform mixture. Required quantities of urea and glycerol were added to this mixture to form a paste. This paste was carefully heated to 100°C initially and finally heated to 460°C for 5 h. The product obtained was subjected to TG/DTA and XRD analysis. The particle size of the cathode material was roughly calculated from the X-ray data using Scherer equation. However, SEM and EDAX analysis were carried out in detail to confirm the particle size and the composition of LiBiO₂ respectively. A 2016 coin type button cell was assembled with LiBiO₂ as cathode and graphite as anode containing polypropylene separator and a solution of 1 M LiClO₄ dissolved in 1:1 (EC+DEC) mixture as the electrolyte. Charge/discharge studies were conducted to establish viability of the reversible cell.

7 illus, 14 ref

015408   Ravindran R (Dep of Math, Indian Inst of Sci, Bangalore-560 012) : Arrow's impossibility theorm. Resonance 2005, 10(11), 18-26.

A number of voting models are considered and the drawbacks of each are indicated. The aim is to develop a voting method, which is based on individual preferences and which finally represents the choice of society. Arrow's theorem addresses this problem.

12 ref

015407   Ramasamy S;Smith D J;Thangadurai P; Ravichandran K;Prakash T;Padmaprasad K;Sabarinathan V (Dep of Nuclear Phys, Univ of Madras, Gumdy Campus, Chennai-600 025, Email: sinna_ramasamy@yahoo.com) : Recent study of nanomaterials prepared by inert gas condensation using ultra high vacuum chamber. Pramana J Phys 2005, 65(5), 881-91.

The ultra high vacuum chamber was developed in the Department of Nuclear Physics, University of Madras with the funding from DST, India. This UHV chamber is used to prepare nanocrystalline materials by inert gas condensation technique (IGCT). Nanocrystalline materials such as PbF₂, Mn²⁺-doped PbF₂, Sn-doped In₂O₃ (ITO), ZnO, Al₂O₃, Ag₂O, CdO, CuO, ZnSe:ZnO etc., were prepared by this technique and characterized. Results of some of these materials will be presented in this paper. In solid-state ²⁰⁷Pb NMR on PbF₂ a separate signal due to the presence of grain boundary has been observed. The structural phase transition pressure during the phase transformation from the cubic phase to orthorhombic phase under high pressure shows an increase with the decrease in grain size. Presence of electronic centres in nanocrystalline PbF₂ is observed from Raman studies and the same has been confirmed by photoluminescence studies. AlO₃ was prepared and ⁵⁶Fe ions were implanted. After implantation segregation of ⁵⁶Fe ions was examined by SEM. The oxidation properties of ITO were studied by HRTEM. As against the expectation of oxide coating on individual nanograins of In-Sn alloy, ITO nanograins grew into faceted nanograins on heat treatment in air and O₂ atmosphere. The growth of ITO under O₂ atmosphere showed pentagon symmetry. The PMN was initially prepared by solid-state reaction. Further, this PMN relaxor material will be used to convert into nanocrystalline PMN by IGCT with sputtering and will be studied.

10 illus, 13 ref

015406   Raghu S;Berchmans S;Phani K L;Yegnaraman V (NO, Cent Electrochem Res Inst, Karaikudi-630 006, Email: kanalaphani@yahoo.com) : Nanoparticulate platinum films on gold using dendrimer-based wet chemical method. Pramana J Phys 2005, 65(5), 821-30.

There is a growing interest in devising wet chemical alternatives for physical deposition methods for applications involving thin films, e.g., catalysis. Deposition of platinum on thin gold films is often a problem leading to incomplete coverage and improper adhesion to solid surfaces. Gold substrates often need pre-activation for achieving complete coverage. Demonstrates here that dendrimers with proper functionalities and size work as well-defined nucleating agents and adhesion promoters. This feature is demonstrated using an amine-terminated dendrimer of generation 4.0. This approach allows one to obtain adherent nanoparticulate films of platinum on gold. Unlike other nucleating agents and adhesion promoting compounds, dendrimers have a well-defined ordered structure in terms of their space filling ability. The stability of the films obtained with adsorbed dendrimers is demonstrated using the electrocatalytic reactions of fuels like methanol. The films formed without dendrimers cannot sustain the electro-oxidation currents due to the instability of the films while the films formed with dendrimers can sustain currents for longer duration and for several cycles. The dendrimer-derived Pt films exhibit higher catalytic activity compared to other methods.

10 illus, 2 tables, 17 ref

015405   Prabhu R R;Khadar M K (Dep of Phys, Univ of Kerala, Kariavattom P 0, Thiruvananthapuram-695 581, Email: mabdulkhadar@rediffmail.com) : Characteraization of chemically synthesized CdS nanoparticles. Pramana J Phys 2005, 65(5), 801-6.

II-VI semiconductor nanoparticles are presently of great interest for their practical applications such as zero-dimensional quantum confined materials and for their applications in optoelectronics and photonics. The optical properties get modified dramatically due to the confinement of charge carriers within the nanoparticles. Similar to the effects of charge carriers on optical properties, confinement of optical and acoustic phonons leads to interesting changes in the phonon spectra. Synthesizes nanoparticles of CdS using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The UV-visible absorption, photoluminescence and Raman spectra of the sample are recorded and discussed briefly.

4 illus, 20 ref

015404   Patel H;Sundararajan T;Pradeep T;Dasgupta A; Dasgupta N;Das S K (Dep of Mech Engng, Indian Inst of Technol Madras, Chennai-600 036, Email: skdas@iitm.ac.in) : Micro-convection model for thermal conductivity of nanofluids. Pramana J Phys 2005, 65(5), 863-69.

Increase in the specific surface area as well as Brownian motion are supposed to be the most significant reasons for the anomalous enhancement in thermal conductivity of nanofluids. This work presents a semi-empirical approach for the same by emphasizing the above two effects through micro-convection. A new way of modeling thermal conductivity of nanofluids has been explored which is found to agree excellently with a wide range of experimental data obtained by the present authors as well as the data published in literature.

3 illus, 13 ref

015403   Narayanasamy A (Mater Sci Centre. Dep of Nuclear Phys, Univ of Madras, Guindy Campus, Chennai-600 025, Email: ansuom@yahoo.co.in) : Magnetic properties of nanostructured spinel ferrites and nanocomposite Nd₂Fe₁₄B/α-Fe permanent magnets. Pramana J Phys 2005, 65(5), 893-900.

Presents some of the important magnetic properties of the nano-structured spinel ferrites such as Ni_0.5Zn_0.5Fe₂O₄ and Mn_0.67Zn_0.33Fe₂O₄ and also that of the nanocomposite Nd₂Fe₁₄B/α-Fe permanent magnetic material. The increase in the magnetic transition temperature of Ni-Zn ferrite from 538 K in the bulk state to 592 K when the grain size is reduced to 16 nm is correlated to the enhancement in the AB su-perexchange interaction strength because of an increase in the magnetic ion concentration in the A-site on milling, as shown by the EXAFS and in-field Mossbauer studies. The particle size has been tailor-made by varying the concentration of the oxidant in the case of Mn-Zn ferrite. The critical particle size for the superparamagnetic limit has been found to be 25 nm with an effective magnetic anisotropy constant of 7.78 kJ m^-3 which is about an order of magnitude higher than that of the bulk ferrite. The exchange coupling is found to be strengthened in the nanocomposite magnet Nd₂Fe₁₄B/α-Fe, when the grain boundary anisotropy is removed by thermal annealing and thus facilitating the enhancement of the energy product.

8 illus, 8 ref

015402   Nagappa B;Chandrappa G T;Livage J (Dep of Chem, Cent Coll Campus, Bangalore University, Bangalore-560 001, Email: gtchandrappa@yahoo.co.in) : Synthesis characterization and applications of nanostructural nanodimensional metal oxides. Pramana J Phys 2005, 65(5), 917-23.

Molybdenum oxide nanorods (MO_x-NR) and vanadium oxide nanotubes (VO_x-NT) have been prepared using MoO₃ and V₂O₅ powders as precursors and hexa-decylamine as surfactant via hydrothermal route. Porous nanocrystalline MgO powder has been prepared by a simple and instantaneous solution combustion process using corresponding magnesium nitrate as oxidizer and glycine as fuel. The compounds are characterized by XRD, TG-DTA, SEM, TEM, surface area and porosity measurements. Because of the porous nature having large surface area (107 m²/g) with nanodimension (12-23 nm), MgO powder has been successfully employed as defluoridizing agent for the removal of fluoride (75%) in ground water.

7 illus, 1 table, 15 ref

015401   Mitani Y;Lara J V;Del Rocio Arvizu M;Perez A (NO, Centro Natn de Metrologia, Km 4,5 Carretcra a Los Cues, El Marques Queretaro, Mexico 76241, Email: ymitani@cenam.mx) : Evaluation of proficiency tests by the use of reference value based on the CMCs of an NMI. MAPAN 2005, 20(4), 291-5.

Importance of comparable measurements among countries has been widely recognized in the last decades in the process of development of global economy, where measurements are key issues in the fare trade and social welfare. Recent activities of NMIs developed under the coordination of CIPM/BIPM to develop mutual recognition of calibration and measurements certificates of NMIs are under the framework of Mutual Recognition Arrangement (MRA). Interamerican Metrology System (SIM) is promoting comparison exercises among NMIs or NMI designated laboratories. In the field of Metrology in Chemistry, measurement traceability is achieved mainly by the application of validated methods. In some cases CRMs play critical role in establishing traceability chain. In this work the important role of NMIs in providing proficiency tests with emphasis on traceable measurements and use of reference value based on the measurements of NMI which has demonstrated CMC. Some example of the efforts of CENAM as NMI is described to establish a national traceable measurement system for sector testing laboratories for environmental protection, food analysis and agriculture by disseminating accuracy of national measurements standards through proficiency tests. The use of unique criteria different from z-score is explained and shows the convenient practice to analyze historical performances of one individual laboratories or the group as a whole.

3 illus, 3 tables, 4 ref

015400   Mishra P;Misra A;Mishra S K;Sachan S K (Dep of Phys, D.B.S. Coll, Kanpur-208 012) : Lattice dynamics and the superionic properties of Pb_xCd_1-xF₂ mixed crystals. Indian J Theor Phys 2005, 53(1), 1-24.

Investigations, the lattice dynamical properties of the mixed superionic crystals Pb_xCd_1-xF₂ have been carried out by using Bond Bending Rigid Ion Model {BBRIM). Phonon dispersion relations, phonon density of states and specific heat at constant volume have been calculated. The agreement obtained between theory and experiment at zone centre is excellent for lower IR mode whereas upper IB durates by 4% only. The calculated Raman mode agrees with the experiment within 3% error.

12 illus, 2 tables, 18 ref

015399   Mishra A K;Bansal C (Sch of Phys, Univ of Hyderabad, Hyderabad-500 046, Email: cbsp@uohyd.ernet.in) : Structural and magnetic phase formation in nanophase brass-iron electron compounds. Pramana J Phys 2005, 65(5), 847-54.

Starting with Cu_0.65 Zn_0.35 with an e/a ratio of 1.35 we studied the phase formation in nanophase (Cu_{0.65 Zn0.35)1-xFex alloys in the concentration range 0.1 ≤ x ≤ 0.7 to see the effect of altering the electron concentration. The evolution of bcc phase from the fee phase as a function of Fe concentration was investigated by Mossbauer spectroscopy and X-ray diffraction. The grain size, lattice parameters, and average hyperfine magnetic field distributions were estimated for the nanophase alloys. The fee phase was observed to persist up to 40 atomic per cent Fe substitutions, a mixed (fee + bcc) phase region up to 70 atomic per cent Fe and bcc phase beyond 70 atomic per cent Fe. The magnetic state of the alloys changed from nonmagnetic for x ≤ 0.3 to magnetically ordered state at room temperature for x ≥ 0.33, which lies in the fee phase region. The fee phase alloys of Fe with non-magnetic metals have very low magnetic transition temperatures. However, in this system the room temperature state is unusually magnetic.}

7 illus, 6 ref

015398   Mei W;Okane T;Umedai T (NO, Toshiba Corporation, Kawasaki, Japan, Email: umeda@eng.chula.ac.th) : Solidification behavior in magnetic Nd-Fe-b and Tb-Dy-Fe materials. Trans Indian Inst Meterol 2005, 58(4), 557-69.

Intermetallic phases of Nd₂Fe₁₄B and Tb(Dy)Fe₂ are, in equilibrium, formed by the peritectic reaction. Therefore, when the initial composition has stoichiometric composition of these intennetallics, these phases are impossible to be obtained as a primary phase in equilibrium. To obtain Nd₂Fe₁₄B or Tb(Dy)Fe₂ phase primarily, phase selection of both alloys to crystallize hard magnetic and magnetostrictive phases were first discussed in relation with initial composition and growth rate. Preferred growth direction in unidirectional solidification and single crystal growth, especially, <111> crystal formation, of Tb-Dy-Fe alloys were also discussed.

15 illus, 2 tables, 30 ref

015397   Mehta B R;Singh V N (Thin Film Lab Dep of Phys, Indian Inst of Technol Delhi, Hauz Khas, New Delhi-110 016, Email: brmehta@physics.iitd.ernet.in) : Structural, electrical and gas-sensing properties of IN₂O₃ : Ag composite nanoparticle layers. Pramana J Phys 2005, 65(5), 949-58.

The central objective of this study is to investigate (i) size-dependent properties of In₂O₃ nanoparticles and (it) the role of metal additives in enhancing the gas sensing response. For this purpose, In₂O₃ : Ag composite nanoparticle layers having well-defined individual nanoparticle size and composition have been grown by a two step synthesis method. Thermogravimetric analysis, X-ray diffraction "and transmission electron microscopy have been used to study the effect of post-synthesis heat treatment on the size and structure of the nanoparticles. A first-time unambiguous observation of size-dependent lowering of transformation temperature has been explained in terms of lower cohesive energy of surface atoms and increase in surface-to-volume ratio with decrease in nanoparticle size. The gas sensing studies of In₂O₃ as well as the In₂O₃ : Ag composite nanoparticle layers have been studied as a function of size and composition. In₂O₃ : Ag composite nanoparticle layers with 15% silver show a sensitivity of 436 and response time of 6 s for 1000 ppm of ethanol in air. Ag additives form a p-type Ag₂O, which interact with n-type In₂O₃ to produce an electron-deficient space-charge layer. In the presence of ethanol, interfacial Ag₂O reduces to Ag, creating an accumulation layer in In₂O₃ resulting in increased sensitivity.

10 illus, 12 ref

015396   Medda S K;Mitra M;De S;Pal S;De G (Sol-Gel Div, Cent Glass and Ceram Res Inst, 196, Raja S.C. Mullick Road, Kolkata-700 032, Email: gde@cgcri.res.in) : Metal nanoparticle-doped coloured films on glass and polycarbonate substrates. Pramana J Phys 2005, 65(5), 931-6.

In a program on the development of metal (e.g. Au, Ag, Cu and their alloy) nanoparticles in sol-gel derived films, attempts were made to synthesize different coloured coatings on glasses and plastics. The absorption position of surface plasmon resonance (SPR) band arising from the embedded metal nanoparticles was tailored by controlling the refractive index of the matrix for the development of different colours. Thus different coloured (pink to blue) coatings on ordinary sheet glasses were prepared by generating Au nanoparticles in mixed SiO₂-TiO₂ matrices having refractive index values ranging from about 1.41 to 1.93. In another development, in situ generation of Ag nanoparticles in the inorganic-organic hybrid host leads to the formation of different abrasion resistant coloured coatings (yellow to pink) on polycarbonate substrates after curing. As expected, the SPR peak of Ag or Au is gradually red-shifted due to the increase of refractive index of the coating matrices causing a systematic change of colour.

3 illus, 12 ref

015395   Krishnamurthy H R (Cent For Condensed Matter Theory Dep of Phys, Indian Inst of Sci, Bangalore-560 012, Email: hrkrish@physics.iisc.ernet.in) : Bethe's contributions to solid state theory: a tribute. Resonance 2005, 10(11), 55-69.

Attempts to acquaint the reader with the seminal contributions made by Hans Albrecht Bethe to the area of solid state theory. It should be read in conjunction with the other tributes to Bethe's work that appeared in the October 2005 issue of Resonance.

2 illus, 20 ref

015394   Khandelwal A K;Jain N C (Dep of Math, Govt P.G. Coll, Tonk-304 001) : Unsteady MHD flow of stratified fluid through porous medium over a moving plate in slip flow regime. Indian J Theor Phys 2005, 53(1), 25-35.

The problem of MHD unsteady viscous stratified flow through porous medium due to moving porous plate under slip boundary condition for velocity field and jump in temperature d has been presented. Using perturbation technique the expressions for velocity and temperature distributions, skin-friction and Nusselt number are obtained and are shown graphically for different values of permeability parameter (K), magnetic field parameter (M) and velocity slip and temperature jump parameters (h₁ and h₂), stratification parameter (α) and suction velocity parameter (A). It is being observed that modulus of skin-friction decreases with the increase of K, h₁ and α. Also the Nusselt number is decreased with the increase of K, h₂ and α but the phenomena reverses for the case of h₁.

4 illus, 9 ref

015393   Khan M;Mohanthy S K;Sood A K (Dep of Phys, Indian Inst of Sci, Bangalore-560 012, Email: manas@physics.iisc.ernet.in ) : Optically-driven red blood cell rotor in linearly polarized laser tweezers. Pramana J Phys 2005, 65(5), 777-86.

Authors have constructed a dual trap optical tweezers set-up around an inverted microscope where both the traps can be independently controlled and manipulated in all the three dimensions. Reports our observations on rotation of red blood cells (RBCs) in a linearly polarized optical trap. Red blood cells deform and become twisted in hypertonic phosphate buffer saline and when trapped, experience an unbalanced radiation pressure force. The torque generated from the unbalanced force causes the trapped R.BC to rotate. Addition of Ca⁺⁺ ions in the solution, keeping the osmolarity same, makes the cell membranes stiffer and the cells deform less. Thus the speed of rotation of the red blood cells can be controlled, as less deformation and in turn less asymmetry in shape produces less torque under the radiation pressure resulting in slower rotation at the same laser power.

4 illus, 16 ref

015392   Kapoor O P (NO, Electron Test & Dev Cent, Mohali, Email: opk_etdc@sify.com) : Statistical model to find accuracy of test and measuring instruments when it is not available/given : solution of a quality problem in calibration. MAPAN 2005, 20(4), 311-18.

Power of metrology is best realized when statistics is used to characterize parameters of interest from the data obtained from sample observations. From every process such as calibration, information is extracted upon which decisions can be made. Decision-making concerning metrology always involves uncertainty. Uncertainty characterizes an interval within which the measurement result is expected to lie with a certain probability called confidence interval. Accuracy, however, indicates ability of T&M instruments to make measurements to find closeness of measured value to the true value. Although metrologists prefer to use uncertainty, accuracy too is governing parameter for the specifications of the instrument. The instrument cannot be exploited to its fullest use in case its accuracy is not available, This paper presents a framework of statistical modeling to find accuracy for such type of instruments thereby achieving the resolution of the problem, something that customers will appreciate.

3 illus, 7 tables, 8 ref

015391   Kalele S;Dey R;Hebalkar N;Urban J;Gosavi S W; Kulkarni S K (Dpepartment of Phys, Univ of Pune, Pune 411 007 Fritz-Haber Institute, Faradayweg 4-6, 14195 Berlin, Germany, Email: skk@physics.unipune.ernet.in) : Synthesis and characterization of silica-titania core-shell particles. Pramana J Phys 2005, 65(5), 787-791.

Nearly monodispersed particles of silica were prepared and coated with uniform layers of titanium dioxide in anatase phase by hydrolysis and condensation of titanium butoxide. The coating thickness could be altered by adjusting the concentration of reactants (titanium butoxide and water) and the amount of added silica particles. Different coating thicknesses were deposited and studied using optical absorption spectroscopy, electron microscopy and Fourier transform infra-red spectroscopy. It was found that silica particles of size 170 ± 5 nm were coated with 23±5 nm thick layer of titanium dioxide. Alternatively titania particles of size 340±5 nm were synthesized by controlled hydrolysis of titanium ethoxide in the presence of sodium chloride. These particles were further coated with 135±5 nm thick layer of silica to investigate changes in properties after changing the shell material.

3 illus, 4 ref

015390   Ipe B I;Yoosaf K;Thomas K G (Pliotosciences and Photonics, Regional Res Lab (CSIR), Thiruvananthapuram-695 019, Email: georgetk@md3.vsnl.net.in) : Interfacial properties of hybrid nanomaterials. Pramana J Phys 2005, 65(5), 909-15.

A brief summary of our ongoing efforts to understand the surface properties of nanoparticles using fluorophores, namely pyrene alkanethiols, is presented. Excited state interactions were investigated by varying the length of the spacer group and the concentration of fluorophore. The flexible long alkyl chain tethering pyrene in Au-P2/Au-P3 allows free interaction between fluorophores resulting in excimer formation whereas the in-termolecular interactions are limited in the Au-P1 system due to the restriction imposed by the curvature of spherical gold nanoparticle. A gradual increase in the peak intensity ratio of III/I band of the normal fluorescence of pyrene was observed indicating that the surface of nanoparticle is more polar than the bulk solvent (toluene).

3 illus, 1 table 20 ref

015389   Goyal S L;Mohindra R K (Dep of Appl Phys, Guru Jambhesliwar Univ, Hisar-125 001) : Neutron induced reaction cross-sections of <. Proc Natn Acad Sci India-Sect B 2005, 75(3), 201-8.

Neutron induced reaction cross-sections of ⁴⁵Sc, ⁴⁶Ti, ⁵¹V and ⁵⁴Fe for (n.2n), (n,p), (n.α), (n.d), (n.t) and (n, ³He) reactions have been evaluated in the energy range of 1-20 MeV. Computer codes ALICE-91, SC2N3N, NX-1 and NX-2 have been used for the computations. The computations are based on evaporation model considering the pre-equilibnum emission mechanism under some approximations. The excitation functions of different isotopes have been shown alongwith the available experimental data. The results are in fairly good agreement with earlier results.

16 illus, 1 table, 39 ref

015388   Ghosh P;Patra A (Sol-Gel Div, Cent Glass & Ceram Res Inst, Jadavpur, Kolkata-700 032, Email: apatra@cgcri.res.in) : Understanding the influence of nanoenvironment on luminescence of rare-earth ions. Pramana J Phys 2005, 65(5), 901-7.

Presents an overview of the recent results on upconversion and photoluminescence of rare-earth ions in nanoenvironments. The role of the rare-earth ion concentration, crystal size and crystal phase on the up- and downconversion emission of rare-earth ions in oxide nanocrystals and their underlying mechanisms are discussed. It is also found that the luminescence lifetime of the excited state rare-earth ions is sensitive to the particle crystalline phase and size. The analysis suggests that the modifications of radiative and nonradiative relaxation mechanisms are due to local symmetry structure of the host lattice and crystal size respectively.

3 illus, 21 ref

015387   George T;Joseph S;Mathew S (Nirmala Coll, Muvattupuzha 686 661School of Chem Sci, Mahatma Gandhi University, Kottayam-686 560, Email: sureshmathew@sancharnet.in) : Synthesis and characterization of nanophased silver tungstate. Pramana J Phys 2005, 65(5), 793-99.

Silver tungstate (Ag₂WO₄) nanoparticles in two different morphologies ar prepared by controlling the reaction kinetics of aqueous precipitation. X-ray diffraction studies reveal that the silver tungstate nanoparticles are in the α-phase. SEM image show the rod-like and fiber-like morphologies of the nanoparticles with high aspect ratios. The TGA and DTA studies show the high thermal stability of the nanorods. The aver age crystallite sizes (20-30 nm) of the rod-like silver tungstate estimated from TEM is consistent with the XRD results.

6 illus, 11 ref

015386   Geethakrishnan T;Palanisamy P K (Cent for Laser Technol Phys Dep, Anna Univ, Chennai-600 025) : Generation of phase-conjugate wave in acid blue 7 dye-doped gelatin film. Curr Sci 2005, 89(11), 1894-8.

Authors has presents optical phase-conjugation based on the degenerate four-wave mixing (DFWM) arrangement in gelatin films doped with acid blue 7 dye. The 633 nm beam from a low-power He-Ne laser was split to form two counter-propagating pump beams and one probe beam in the DFWM geometry. Experiments were carried out by varying the parameters (angle of separation between the forward-pump and the probe beam, concentration of the dye in the gelatin film, writing beam intensities) that influence the phase-conjugate beam reflectivity. High reflectivity optical phase-conjugation is hereby reported for low-power lasers.

11 illus, 23 ref

015385   Ganguli A K;Ahmad T;Arya P R;Jha P (Dep of Chem, Indian Inst of Technol Delhi, New Delhi-110 016, Email: ashok@chemistry.iitd.ernet.in) : Nanoparticles of complex metal oxides synthesized using the reverse-micellar and polymeric precurso routes. Pramana J Phys 2005, 65(5), 937-47.

Current interest in the properties of materials having grains in the nanometer regime has led to the investigation of the size-dependent properties of various dielectric and magnetic materials. Discusses two chemical methods, namely the reverse-micellar route and the polymeric citrate precursor route used to obtain homogeneous and monophasic nanoparticles of several dielectric oxides like BaTiO₃, Ba₂TiO₄, SrTiO₃, PbTiO₃, PbZrO₃ etc. Also discusses the synthesis of some transition metal (Mn and Cu) oxalate nanorods using the reverse-micellar route. These nanorods on decomposition provide a facile route to the synthesis of transition metal oxide nanoparticles. Discusses the size dependence of the dielectric and magnetic properties in some of the above oxides.

7 illus, 32 ref

015384   El-Gazery M;Amer A (Natn, Inst for Stand, (Egypt), Email: elgazery@sit.nis.sci.eg) : Reference blocks development for ultrasonic thickness gauge calibration. MAPAN 2005, 20(4), 273-82.

Ultrasonic thickness measuring instruments need to be periodically calibrated against a reference material with known dimension and velocity indues. Describes a procedure for development of reference blocks used in calibration of such instruments. Ten cylindrical steel blocks with different thickness (10, 20 ... 100 mm) and 40 mm diameter were established. Comparison measurements between mechanical and ultrasonic thickness measurements were carried out on these blocks. Different thickness gauges with different attached probes were evaluated using these blocks. It was found that the ultrasonic measurements and uncertainties are affected by the roughness of the probe contact surface with the blocks. The uncertainty of measurements is affected by the display resolution of the used instruments too.

7 illus, 4 tables, 16 ref

015383   Das N;Dey G K;Murty R S;Pabi S K (Metall and Mater Engng Dep, Indian Inst of Technol, Kharagpur-721 302, Email: skpabi@metal.iitkgp.ernet.in) : On amorphization and nanocomposite formation in Al-Ni-Ti system by mechanical alloying. Pramana J Phys 2005, 65(5), 831-40.

Amorphous structure generated by mechanical alloying (MA) is often used as a precursor for generating nanocomposites through controlled devitrification. The amorphous forming composition range of ternary Al-Ni-Ti system was calculated using the extended Miedema's semi-empirical model. Eleven compositions of this system showing a wide range of negative enthalpy of mixing (ΔH^mix) and amorphization (ΔH^amor) of the constituent elements were selected for synthesis by MA. The Al₈₈Ni₆Ti₆ alloy with relatively small negative ΔH^mix (-0.4 kj/mol) and ΔH^amor (-14,8 kJ/mol) became completely amorphous after 120 h of milling, which is possibly the first report of complete amorphization of an Al-based rare earth element free Al-TM-TM system (TM = transition metal) by MA. The alloys of other compositions selected had much more negative ΔH^mix and H^amor but they yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the as-milled condition, evidencing a high degree of stability of the intermetallic phases under the MA environment. Hence, the negative ΔH^mix and ΔH^amor are not so reliable for predicting the amorphization in the present system by MA.

8 illus, 34 ref

015382   Chowdhury D (Dep of Phys, Indian Inst of Technol, Kanpur-208 016, Email: debch@iitk.ac.in) : 100 years of Einstein's theory of Brownian motion: from pollen grains to protein trains-2. Resonance 2005, 10(11), 42-54.

Rotational Brownian motion and Brownian shape fluctuations of soft materials are discussed. This is followed by an elementary introduction to two of the hottest topics in this contemporary area of interdisciplinary research, namely, stochastic resonance and Brownian ratchet.

5 illus

015381   Chakrabarti C G;Sarkar N G;De M K (Dep of Appl Math, Univ of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009) : Statistics of binary system:stability, fluctuation and critical phenomena. Indian J Theor Phys 2005, 53(1), 79-88.

A statistical theory of fluctuation of an open binary system and study its role in the characterization of stablity and critical phenomena in the binary system have been presented and studied.

11 ref

015380   Bhaumik A;Samanta S;Mal N K (Dep of Mater Sci, Indian Ass for the Cultivation of Sci, Jadavpur, Kolkata-700 032, Email: msab@mahendra.iacs.res.in) : Iron oxide nanoparticles stabilized inside highly ordered mesoporous silica. Pramana J Phys 2005, 65(5), 855-62.

Nanosized iron oxide, a moderately large band-gap semiconductor and an essential component of optoelectrical and magnetic devices, has been prepared successfully inside the restricted internal pores of mesoporous silica material through in-situ reduction during impregnation. The samples were characterized by powder XRD, TEM. SEM/EDS, N₂ adsorption, FT-IR and UV-visible spectroscopies. Characterization data indicated well-dispersed isolated nanoclusters of (Fe₂O₃)_n within the internal surface of 2D-hexagonal mesoporous silica structure. No occluded Fe/Fe₂O₃ crystallites were observed at the external surface of the mesoporous silica naiiocomposites. Inorganic meso-porous host, such as hydrophilic silica in the pore walls, directs a physical constraint necessary to prevent the creation of large Fe₂O₃ agglomerates and enables the formation of nanosized Fe₂O₃ particles inside the mesopore.

4 illus, 1 table, 24 ref

015379   Basheed G A;Kaul S N (Sch of Phys, Univ of Hyderabad, Hyderabad-500 046, Email: kaulsp@uohyd.ernet.in) : Ferromagnetic resonance investigation of nanocrystalline FeCuNbSiB. Pramana J Phys 2005, 65(5), 841-6.

An elaborate line-shape analysis of the ferromagnetic resonance (FMR) spec-tra taken in the temperature range 100 K to 350 K on amorphous FeCuNbSiB alloys before and after nanocrystallizing them reveals that in the nanocrystalline state, (i) spin wave stiffness (D) is enhanced while the saturation magnetization, MS, is reduced, (ii) both the 'in-plane' anisotropy field, H_K, as well as the FMR line-width scale with Ms, (iii) the single-ion anisotropy of spin-orbit plus crystal field origin dominates over the two-ion anisotropy of dipolar origin and (iv) multi-magnon scattering contributions to FMR line-width become important in some cases.

4 illus, 1 table, 7 ref

015378   Bagga E;Kumari S;Kumar R;Kumar R;Bajpai R P; Bharadwaj L M (Biomolecular Electron and Nanotechnology Div, Cent Scientific Instrument Organisation, Sector 30/C, Chandigarh-160 030, Email: bharadwajlalit@yahoo.com) : Covalent immobilization of myosin for in-vitro motility of actin. Pramana J Phys 2005, 65(5), 967-72.

The study reports the covalent immobilization of myosin on glass surface and in-vitro motility of actin-myosin biomolecular motor. Myosin was immobilized on poly-L-lysine coated glass using heterobifunctional cross linker EDC and characterized by AFM. The in-vitro motility of actin was carried out on the immobilized myosin. It was observed that velocity of actin over myosin increases with increasing actin concentration (0.4-1.0 mg/ml) and was found in the range of 0.40-3.25 microm/s. The motility of actin-myosin motor on artificial surfaces is of immense importance for developing nanodevices for healthcare and engineering applications.

4 illus, 22 ref

015377   Anthony S P;Porel S;Rao D N;Radhakrishnan T P (Sch of Chem Sch of Phys, Univ of Hyderabad, Hyderabad-500 046, Email: tprsc@uohyd.ernet.in) : Thin films of metal-organic compunds and metal nanoparticle-embedded polymers for nonlinear optical applications. Pramana J Phys 2005, 65(5), 871-9.

Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which form perfectly polar assemblies in their crystalline state are found to organize as uniaxially oriented crystallites in vapor deposited thin films on glass substrate. Optical second harmonic generation from these films is investigated. A simple protocol is developed for the in-situ fabrication of highly monodisperse silver nanoparticles in a polymer film matrix. The methodology can be used to produce free-standing films. Optical limiting capability of the nanoparticle-embedded polymer film is demonstrated.

8 illus, 17 ref

015376   Agrawal V V;Thomas R;Kulkarni G U;Rao C N R (Chem amd Phys of Mater Unit, Jawaharlal Nehru Cent for Advd œ Reasearch, Jakkur, Banglore-560 064, Email: cnrrao@jncsar.ac.in) : Single molecule switch based on two Pd nanocrystals linked by a conjugated dithiol. Pramana J Phys 2005, 65(5), 769-75.

Tunneling spectroscopy measurements have been carried out on a single molecule device formed by two Pd nanocrystals (dia. <126>5 nm) electronically coupled by a conducting molecule, dimercaptodiphenylacetylene. The I-V data obtained by position ing the tip over a nanocrystal electrode, exhibit negative differential resistance (NDR) a background M-I-M characteristics. The NDR feature occurs at <126>0.67 V at 300 K and shifts to a higher bias of 1.93 V at 90 K. When the tip is held in the middle region of the device, a Coulomb blockade region is observed (±<126>0.3 V).

5 illus, 26 ref

015375   Agarwala R C (Metall and Mater Engng Dep, Indian Inst of Technol Roorkee, Roorkee-247 667, Email: ramesfmt@iitr.ernet.in) : Electroless Ni-P-ferrite composite coatings for microwave applications. Pramana J Phys 2005, 65(5), 959-65.

Electroless, EL coating technique is one of the elegant ways of coating by controlling the temperature and pH of the coating bath in which there is no usage of electric current. It is estimated that the market for this chemistry will increase at a rate of about 15% per year. Use of microwave energy for synthesis of material with novel microstructures is an exciting new field in material science with enormous application. In this investigation, nanograined BaZn_22-yCo_y Fe₁₆O₂₇ (y = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) powders have been synthesized by citrate precursor method followed by heat treatment at various specified temperatures like 650, 750 and 850°C for 3 h in the furnace. In addition heat treatments are also carried out in the microwave oven of the power rating of 760 W. The powders thus produced have been characterized by SEM, EPMA, VSM, XRD and thermal analysis techniques. As a forward step towards EL nano-composite coatings, Ni-P-X (X = BaZn_2-yCo_y Fe₁₆O₂₇) coatings with thickness less than <126>0.1 mm thick has been produced. Such coating exhibits absorption of microwave in the range of 12-18 GHz up to about 20 db depending upon the volume fraction of the ferrite particles embedded in the Ni-P matrix.

6 illus, 3 ref

015374   Abdullah A;Annapoorni S (Dep of Phys and Astrophys, Univ of Delhi, Delhi-110 007, Email: annapoorni@physics.du.ac.in) : Fluorescent silver nanoparticles via exploding wire technique. Pramana J Phys 2005, 65(5), 815-19.

Aqueous solution containing spherical silver nanoparticles of 20-80 nm size have been generated using a newly developed novel electro-exploding wire (EEW) technique where thin silver wires have been exploded in double distilled water. Structural properties of the resulted nanoparticles have been studied by means of X-ray diffractome-ter (XRD) and transmission electron microscopy (TEM). The absorption spectrum of the aqueous solution of silver nanoparticles showed the appearance of a broad surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. The theoretically generated SPR peak seems to be in good agreement with the experimental one. Strong green fluorescence emission was observed from the water-suspended silver nanoparticles excited with light of wavelengths 340, 360 and 390 nm. The fluorescence of silver nanoparticles could be due to the excitation of the surface plasmon coherent electronic motion with the small size effect and the surface effect considerations.

4 illus, 8 ref

014304   Trivedi U N;Chhantbar M G;Modi K B;Joshi H H (Depanment of Phys, Saurashtra Univ, Rajkot-360 005) : Frequency dependent dielectric behaviour of cadmium and chromium co-substituted nickel ferrite. Indian J pure appl Phys 2005, 43(9), 688-90.

The frequency dependent dielectric properties of N_1-xCd_xCr_xFe_2-xO₄ (x = 0.0, 0.3, 0.5, 0.7 and 1.0) spinel ferrite system are studied by measuring dielectric constant (ε')> dielectric loss (D) and conductivity (σ_a.c) at 300 K in the frequency range 100 Hz-2 MHz. The highest value of σ_a.c. and ε' is observed for x = 0.3 composition. The values ε' and σ_a.c decrease with increase in frequency for all the compositions, exhibiting normal ferrimagnetic behaviour and are attributed to Maxwell-Wagner type interfacial polarization. The observed broadening of relaxation peak with content in dielectric loss versus frequency curve is due to the strengthening of dipole-dipole interactions.

1 illus, 10 ref

014303   Tajalli H;Ehsani H;Ahmadi S (Res Inst for Appl Phys and Astr, The Univ of Tabriz, Tabriz-51664-163, Iran, Email: tajalli@tabrizu.ac.ir) : Dynamical behavior of photoinduced birefringence in DSR1-PMMA by using pulsed laser. Indian J Phys 2005, 79(10), 1207-9.

Photoinduced birefringence in PMMA-DSR1 system has been investigated using Nd³⁺-YAG pulsed laser with wavelength of 532 nm which is in the near resonance with absorption line of trans isomer of azobenzene molecules. The effects of parameters such as pumping intensity, pulse repetition rate in the induced birefringence have been studied, using a probe He-Ne laser.

5 illus, 11 ref

014302   Sundharam N;Palaniappan L (Dep of Phys (DDE), Annamalai Univ, Annamalainagar-608 00, Email: lp_dde_au@yahoo.com) : Molecular interaction studies in the ternary mixture of methanol + benzene + cyclohexane. Indian J Phys 2005, 79(10), 1173-8.

The values of sound velocity, density and viscosity have been measured at 308 K in the system methanol + benzene + cyclohexane. From these data acoustical parameters such as adiabatic compressibility, free length, free volume and internal pressure have been estimated using the standard relations. The deviations of the sound velocity from that of experimental values are obtained using Nomoto's relation (NR), ideal mixing relation (IMR), free length theory (FLT), collision factor theory (CFT) and Nutsch-Kuhnkies (NK) method. The results are interpreted in terms of molecular interaction between the components of the mixtures. Methanol is found to be a good structure breaker that breaks the cyclohexane-benzene complexes. The excess values obtained confirms the presence of weak interaction in the system.

5 illus, 2 tables, 36 ref

014301   Suhail M A;Neelofer N;Khan Z A (Dep of Appl Phys, Z.H. Coll of Engng and Technol, Aligarh Muslim University, Aligarh-202 002) : Relativistic analysis of nuclear ground state densities at 135 to 200 MeV. Pramana J Phys 2005, 65(6), 1027-40.

A relativistic analysis of p + ⁴⁰Ca elastic scattering with different nuclear ground state target densities at 135 to 200 MeV is presented. It is found that the IGO densities are more consistent in reproducing the data over the energy range considered. The reproduction of spin-rotation-function data with the simultaneous fitting of differential cross-section and analyzing power, and the appearance of wine-bottle-bottom shaped Re U_eff (τ) in the transition energy region, sensitively depends on the input nuclear ground state densities and are not solely the relativistic characteristic signatures. Also finds that the wine-bottle-bottom shaped ReU_eff (τ) is preferred by the spin observables in the transition energy region (i.e. 181 MeV to 200 MeV).

7 illus, 2 tables, 23 ref